Farhan’s website at www.hfsigs.com. The instructions and
documentation are well written and comprehensive.

Farhan himself has created some You Tube videos which
explain in detail how the BITX40 works.

It’s hard to improve on Farhan’s instructions, but here
are a few thoughts for the novice builder, from my
building experience:

(A). The builder is instructed to keep wires as short as
possible. This is recommended, but I found it best not to
cut the wires until I’d worked out the orientation of the
main board and other parts within my enclosure. Since I

plan to make future modifications to my BITX40, I didn’t
remove very much from my wires. I was careful to wrap
the wires and (as best I could) keep them away from the
board. So far, I haven’t noticed any negative effect on
operation of my rig.

(B). The BITX40 is built for tinkering and
experimentation, and I plan to do both. With that in mind,
I decided to use an external speaker instead of placing a
speaker inside the enclosure. I wanted to leave as much
space as possible inside. Surprisingly, I can hear a little
better too.

(C). Making or finding a suitable enclosure for the
BITX40 added to the fun of the build. Almost any
enclosure will work, as long as there’s space enough for
the main board, and openings for the antenna connector,
volume control, and other parts which need to be
accessible from outside the enclosure. I’ve found that the
most difficult part of making an enclosure from scratch is
cutting the opening for the LCD. The unit I’m using is one
I took from a vintage frequency counter that I had gotten
for free at a ham radio swap meet. It already had the
necessary opening for the LCD, so I removed the vintage
circuitry and drilled holes for the tuning and volume
potentiometers, the mic, and the antenna connector. I
placed the hole for the power connector in the back.

(D). The mic which comes in the BITX40 kit is an
electret condenser type. It works quite well; however, this
mic is small and the kit doesn’t come with any type of
holder. Without any kind of case, the mic can be difficult
to hang on to. I used the handle from an old hobby knife
to make a holder for the electret mic. The toggle switch
on the right of my enclosure is used for the PTT switch.
Some builders have used a ball point pen as a holder for
their mic, and others have used a small piece of PVC. Still
others have replaced the electret mic altogether and
converted to an HM- 36 hand mic or an old four-pin CB
mic. If it works for you, then it’s a good solution.

(E). There is a three-pin connector on the board which
is marked “tuning.” This was once used to connect the
tuner, prior to using digital tuning. Now that the BITX40
uses digital tuning, this connector is no longer used and
can be ignored. The digital VFO should be attached to the
connector for DDS.

(F). The instructions for connecting the tuning and
volume potentiometers tell the builder to solder the wires
from left to right. Novice builders might find this a little
confusing. To avoid any mistakes, this instruction means to
solder left to right while facing the front of the
potentiometer.

(G). To make calibration a little easier, I left the
calibration circuitry inside the enclosure so it will be
available any time my rig needs to be calibrated. It works
well, and it has been necessary to calibrate more than
once. Just remember that it’s important to stow this
circuitry in a place where it won’t make contact with
ground. If it does connect with ground, the tuner will
automatically go into calibration mode and the tuner will
require recalibration.

(H). I placed the antenna connector at the front of my
enclosure because I was following along with the
schematic on the instruction sheet. It’s certainly functional

Parts for the BITX40. The LCD is at the lower left and the
Raduino (Arduino Nano) and Si5351 synthesizer are on
the right.

Assembled BITX40 before going into the enclosure. From
upper left going clockwise: PTT (green switch), power
connector, Raduino and tuning pot, speaker, volume pot,
and antenna connector. Mic is not shown.